Crankcase ventilator



a United States Patent [72] Inventor JoeW. Von Brimer 1209 Commerce, LasVegas, Nevada 89102 [21] Appl. No. 756,591 [22] Filed Aug. 30, 1968 [45]Patented Dec. 8,1970

, [54] CRANKCASE VENTILATOR 10 Claims, 4 Drawing Figs.

[52] U.S.Cl 123/119, 123/198; 230/92. 230/95 [51] Int. Cl ..F02m 25/06;FO4f 5/16 [50] Field oiSearch 123/119(A), 119(8), 1 19, 198(C), 198;230/92. 95

[56] References Cited UNITED STATES PATENTS 1,780,626 11/1930 'Mclntosh123/119 2,068,363 l/l937 Wetmore et a]. 230/92 3,146,768 9/1964Osborne... 123/119 3,306,525 Dornier 230/95 3,362,386 l/l968 McMahonPrimary Examiner-Wendell E. Burns Attomey--Greist, Lockwood, Greenawalt& Dewey ABSTRACT: A crankcase ventilator or positive crankcaseventilation system in which a portion of the exhaust gases created by aninternal combustion engine are passed through a vacuum chamber whereinan at least partially curvilinear flow pattern is imparted thereto, andwherein the centrifugal force associated with such flow pattern createsa vacuum which is used to, draw vapors, fumes, and thejlike from theengine PATENTEU DEC 8 I976 IN VE N 70R W. VON BRIMER ATT'YS.

CRANKCASE YENTILATOR l BACKGROUND OF THE INVENTION 1. Field of theInvention e e i The field .of the invention is that of accessories forinternal combustion engines, and particularly that of crankcaseventilation systems for usein extracting crankcase vapors from thecrankcase and recirculating them throughthe combustion chamber andexhaust system of the engine after they have been extracted. The fieldis also thatof devices for imparting a curvilinear flow pattern tofastmoving gas streams and for utilizing the vacuum created by thecentrifugal force associated with the flow pattern of such gas streamsfor extracting vapors from engine crankcases, and entertaining them inthe streams forrecirculation into the combustion chamber of the engine.v

2. Description of the Prior Art Recently, there has been an increasedawareness of the need for positive crankcase ventilation (PCV) systems,since.

studies have shown that considerable air pollution may be caused by theentry into the air of various combustion products and byproducts,including oxides of nitrogen, burned and unburned hydrocarbon residues,oil vapor, and other combustion products, such as acids and the like.Most crankcase ventilation devices of the prior art, and particularlythose which are presently in large scale use, utilize intake manifoldvacuum for drawing the crankcase vapors from the crankcase, generallythrough an opening in a portion of the cover for the valve rocker arms,and moving such vapors through a gravity operated, normally closedneedle valve, and allowing them to enter the intake manifold of theengine, generally immediately below or downstream of the venturi area orthrottle body of the carburetor. i 1

However, then systems have certain drawbacks. Most objectionablecrankcase vapors are caused by blowby", that is,

passage of high-pressure combustion ,gases downwardly toward thecrankcase between the cylinders and the piston ring assembly. Blowby isat a maximum when cylinder pressures are highest, and cylinder pressuresare greatest when type have not been free of difficulty, arecharacterized by this inherent relation of vacuum-to-blowby, and haveincluded at least one movable part, the valve.

In addition, priorart PCV systems have required frequent servicing, andits known by manufacturers that neglect of maintenance on PCV systemscreates many problems, such as increased gas and oil consumption, oildilution and other adverse effects.

SUMMARY OF THE INVENTION Accordingly, in view of the drawbacks ofcrankcase ventilator devices of the prior art, an object of theinvention is to provide a crankcase ventilation system which isresponsive to the condition of the engine so to provide maximumextraction and recirculation of crankcase vapors when maximum blowby isoccurring, as well as a certain amount of exhaust gas recirculation.

which has no mechanical moving parts and which is simple and reliable inuse.

Another object of the invention is to provide a crankcase A furtherobject is to provide a crankcase ventilation system i created bycirculating exhaust gases through the chamber and into the intakeairstream of the engine. A further object is to provide a crankcaseventilator in which recirculated exhaust gases are entrained in theairstream of the carburetor of the engine.

Another object of the invention is to provide crankcase ventilator inwhich recirculated crankcase vapors are evenly diffused in the intakeairstream.

Another object is to provide a crankcase ventilator system whichincludes means for ventilating the crankcase and for simultaneouslyrecirculating a significant portion of the exhaust gases through theengine.

Another object of the invention is to provide a crankcase ventilationsystem which will not affect the vacuum condition of the intake manifoldof the engine.

The present invention achieves these objects, and others which areinherent therein, by providing a vacuum chamber having at leastpartially curvilinear sidewall portion, two end wall portions,combustion gas inlet means disposed tangentially to the sidewall,crankcase vapor inlet means in an end wall of the chamber at a pointspaced radially inwardly from the sidewall, an outlet means in thechamber for supplying the exhaust gases with the crankcase vaporsentrained therein to the intake airstream of an engine for recirculatingvapors and gases therethrough.

The exact manner in which this invention achieves the above-statedobjects, and other objects which are inherent therein, will appear moreclearly when reference is made to the description of the preferredembodiments of the invention,

and to the drawings, in which like reference numerals indicatecorresponding parts throughout.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view,partly diagrammatic, and having portions broken away, showing a portionof an internal combustion engine and the crankcase ventilator unit ofthe invention associated therewith.

FIG. 2 is a vertical sectional view of the vacuum chamber portion of thecrankcase ventilator of the invention.

FIG. 3 is a graph showing the vacuum characteristics obtainable with thecrankcase ventilator of the invention.

FIG. 4 is a horizontal sectional ,view taken on lines 4-4 of FIG. 2,showing the vacuum chamber thereof. DESCRIPTION OF THE PREFERREDEMBODIMENTS Before describing the invention in greater detail, it willbe understood that as used herein, the terms gas, vapor, and the likeare used in an ordinary understood and not in a technical sense, thatis, it is not implied that the gases or vapors, or mixtures thereof, areso characterized because of critical temperature, pressure or the like,but are so characterized because of ordinary references thereto by suchterms.

Referring now to FIG. 1, the crankcase ventilator 20 of the invention isshown to be associated with an internal combustion engine, generallyindicated at 22. The engine 22 ineludes an air cleaner and silencerassembly 24 having an air intake duct 26, an air filter 28, an inner,:fresh air chamber 30, a bottom wall portion 32 supporting a fitting 34which surrounds an opening in the bottom wall position 32 of theassembly 24.

The engine 22 also includes a carburetor, generally shown at 36, and thecarburetor 36 includes a float chamber and venturi section 38, athrottle body portion 40 and an intake air horn portion 42. An intakemanifold 44, has a plurality of passages 46 situated between thecarburetor 36 and the comvalve 56, a combustion chamber 58, a valvetrain assembly 60,

ventilation system which includes a vacuum chamber operativelyassociated with the 'crankcase,jand in which vacuum is which includesconventional valve gear such as push rods, rocker arms shafts andstands, valve springs and the like. A valve cover unit 62.covers theopen portion of the top of the cylinder head 52. An exhaust manifold 64,having an opening 66 therein, which will be described more fully herein,is included for guiding the exhaust gases leaving the combustion chamber58 into the remainder of the exhaust system (not shown), which isconventional and may include head pipes, mufflers and the like. lnreference to the engine 22, it will be understood that the portions ofthe engine beneath the camshaft cover member 68, and beneath the valvecover 62 as well as in the area surrounded by the oil pan 48, and otherportions on the interior of the engine, are in a substantially airtightrelation to the exterior of the engine, in keeping with modern enginedesign practices directed to minimizing or eliminating air pollution.Therefore, this area, namely those portions of the engine which are invapor communication with the oil sump, is collectively referred to asthe crankcase 69 for purposes of description herein. Thus the crankcaseincludes all internal portions of the engine, excluding only thecombustion chambers, intake and exhaust ports and manifolds, and coolantpassages and the like.

Referring now to the crankcase ventilator unit in greater detail, theunit 20 is shown to include a body 70, having a finned exterior surface72, a combustion gas inlet tube 74, to which is attached a gas conduit76, a gas-vapor outlet tube 78, to which is connected a gas-vaporconduit 80, and an end cover plate 82 having a vapor inlet tube 84extending therethrough. The vapor inlet tube 84 is connected to aconduit 86 having an end 70 88 which terminates in a fitting 90, whichattached to the valve cover 62, thus placing the interior of thecrankcase in communication with the interior ofthe conduit 86. Thegas-vapor conduit 80 extends between the gas-vapor outlet 78 and thefitting 34 disposed in the bottom wall portion 32 of the clean airchamber 30 of the air cleaner and silencer assembly 24.

Referring now to FIG. 2, it is shown that the body 70 includes acombustion gas inlet port 92, forming a part of or being in registrywith the gas inlet tube 74, a gas-vapor outlet port 94 forming a part ofor being in registry with the gasvapor outlet tube 78, and an at leastpartially curvilinear inner sidewall portion 96,.extending between theinlet and outlet ports 92, 94 for directing gases entering the tube 74along the .wall 96 and out the port 94 and tube 78.

Referring now to FIG. 4, it will be seen that the ports 92 and 94 arecircular in cross section, that the curvilinear sidewall 96 is flat, andthat the end walls 82, 98 are also generally flat. The

vapor inlet port 100 is disposed centrally of the 'cover plate 82 and isformed as a part of or in registry with the vapor inlet tube 84.However, the areas, sizes and shapes of the body 20 of the vacuumchamber portion 79 are not critical, it being understood thatdescription herein is made only of a simple, representative form of theinvention which is economical to manufacture and dependable in use.

Referring again to FIG. 2, with a stream of gases entering the tube 74at high velocity and assuming the disposition shown by the arrows, avacuum occurs in the center and in other portions of the body 20 whichare spaced radially inwardly from the sidewall 96, since the curvilinearflow pattern forces the gas molecules toward the wall 96 by centrifugalforce, thereby creating a low-pressure area in the middle of the chamber20. Vapors are pulled from the crankcase through the opening in thevalve cover 62 which is defined by the fitting 90 and the end portion 88of the conduit 86. The gas-vapor mixture thus formed in the chamber 20is directed into the clean air portion 30 of the air cleaner andsilencer assembly 24, where it is entrained into airstream above orupstream of the air horn 42 of the carburetor 36.

As a result, a minor but significant portion of the exhaust gases whichwould otherwise be directed into the exhaust manifold 64 arerecirculated through the carburetor 36 and into the combustion chamber58. Studies have shown that, in the interest of greatly reducinghydrocarbons, nitrogen oxides, and other like residues which causesignificant air pollution, it is beneficial to recirculate up to about12 percent of the exhaust gases from an engine back into the intakeairstream. Ac-

cordingly, this invention accomplishes'an object of recirculatingcombustion or exhaust gases and has a further advantage of being agreatly improved positive crankcase ventilator for reasons which willnow be discussed. 1

Referring now to FIG. 3, there is illustrated in graphic form therelation between vehicle speed, and crankcase pressure or vacuum. Theline 102 shown below the horizontal or zero" reference line 104represents actual measurements made on the crankcase of a used auto inaverage good condition, utilizing a conventional positive crankcaseventilation recirculation system of the type in use today, with theneedle valve removed, and the line 106 represents measurements made onthe crankcase of an auto equipped with the crankcase ventilator of thepresent invention.

As can be seen from line 102, contrary to expectations, an actual vacuumcondition does not ordinarily exist in a typical engine crankcase undernormal conditions. The closest approach to an actual vacuum conditionoccurs when the auto is going slowly with moderate throttle settings,and when, as shown at line 108 of the graph, the throttle is closed andthe engine is allowed to decelerate. As a result, it can be seen thatwith the prior art PCV system, if vapors are tending to leave thecrankcase, they are doing so at a limited rate, since they exist insufficient quantity to cause the overpressure shown, namely, up to about3.5 inches of water. Although the invention herein is not intended to belimited by any particular theory of operation, particularly in regard toprior devices, it is believed that in normal use, the manifold vacuumdeveloped in an engine under conditions wherein most crankcase vaporsare generated, and when the need for crankcase ventilation is thereforemost important the blowby volume exceed that which is able to beentrained into the intake manifold below the throttle body. As a result,more blowby is created therein than can be accommodated'by manifoldvacuum, it being understood that conditions of high-speed, open throttleoperation and rapid acceleration create least amount of manifold vacuumand the greatest amount of blowby.

On the other hand, as may be seen by reference to line 106 in FIG. 3,the amount of actual crankcase vacuum able to be obtained by thecrankcase ventilator of the present invention depends primarily on thevelocity and volume of the exhaust or combustion gases. Since thevelocities and volumes increase as engine speed increases and as thethrottle is more fully opened, more vacuum is available as more blowbytends to be created, and accordingly, the crankcase ventilator of thepresent invention is able to maintain a negative pressure (gage) orpartial vacuum in the crankcase at all times of significant vaporgeneration, and at high speeds, the actual vacuum may be 2 inches ofwater or more. In reference to this description, it will be understoodthat the vacuum which is being measured is actual crankcase vacuum, notmanifold vacuum.

A further advantage of the present invention is that much widerdistribution and much better mixing of recirculated exhaust gases in theintake airstream is made possible. Thus, in prior art PCV systems thefuel-air mixture established at the carburetor was susceptible to beingaltered by bleeding crankcase vapors into the manifold below thethrottle body. In addition to changing the mixture, there was a dangerthat if the hose or tube leading to the manifold were to be accidentallyremoved, or developed a leak, air would enter the manifold, causing anexcessively lean mixture and presenting the possiblity of excessivelyfast idle speed, detonation or preignition, and consequent damage tovalves, pistons, and the like.

However, the present invention enables the vapor-gas mixture to bedelivered to the airstream above or upstream of the carburetor, so thatthese elements, namely, crankcase vapors and exhaust gases, are alreadyin the intake airstream when the air-fuel mixture ratio is establishedat the carburetor venturi. In addition, the gas-vapor mixture isdistributed better then it would be if it were allowed to enter themanifold at a point beneath the carburetor, because of the greaterdistance to the intake ports, the turbulence induced by the venturi,etc.

In addition, a reduced amount of undesirable emissions through theexhaust systems is made possible, since, in the present invention theamount of recirculated exhaust or combustion gas is approximatelydirectly proportional to the speed and power output of the engine,rather than being dependent on manifold vacuum, and accordingly, havingan inversely proportional degree of recirculation.

Referring now to FIGS. 2! and 3, it is shown that approximately a 180angle exists between the tubes 74 and 78. Likewise, the chamber has beendescribed with reference to the shape shown in FIGS. 2 and 3. However,the tubes 74, 78 may be separated to a greater or lesser degree,provided only that a curvilinear flow is imported to a stream of theexhaust gases. If more than one turn (360) of the gas stream within thechamber 79 is desired, the tubes 74, 78 may be offset from each otheralong the axis of the chamber and inclined slightly toward each other.The end walls 82, 98 and the sidewall 97 need not be flat, but may be ofany other suitable shapes, and the ports 92, 94 may havecross-sectionalshapes other than circular. The gas vapor mixture ispreferably entrained in the airstream above the carburetor, but it neednot be disposed in the air cleaner exactly as shown. Although the sizeand number of the ventilator units are not a critical feature of theinvention, the ventilator has performed excellently with the vacuumchamber 79 having an inside diameter of about 3 inches, and width of l Ainches. The conduits 76, 80, 86 were typically of about three-eights ofan inch, three-quarters of an inch and a an, inch diameters,respectively. As pointed out above, since the unit has no moving parts,mechanical failure, clogging, etc., are of minimal likelihood ofoccurence.

. It will thus be seen, by reference to the foregoing, that the presentinvention provides a novel crankcase ventilator having numerousadvantages and characteristics, including those hereinbefore pointedout, and others which are inherent in the invention.

1 I claim:

l. A crankcase ventilator system for an internal combustion engine, saidsystem comprising, incombination, means for imparting a curvilinear flowpattern to a stream of combustion gases from the exhaust system of aninternal combustionengine so that the centrifugal 'force resulting fromsaid flow pattern creates a vacuum region adjacent the region ofcurvilinear flow, means for connection to the crankcase of an engine forsupplying crankcase vapors generated by said engine to said vacuumregion to entrain said crankcase vapors into said stream of combustiongases, and means for supplying the stream of combustion gases, with thecrankcase vapors entrained therein to the intake airstream of aninternal combustion engine.

2. A crankcase ventilator system as defined in claim 1 in which saidmeans for imparting said curvilinear flow pattern comprises a chamberhaving a curvilinear sidewall portion.

.3. A crankcase ventilator system as defined in claim 1 in which saidmeans for imparting said cuwilinear flow pattern comprises a chamberhaving a curvilinear sidewall portion and wherein said means furtherincludes inlet and outlet means for said stream of gases, said inlet andoutlet means being disposed tangentially to said sidewall portion.

a gas stream of gases, said inlet :and outlet means being disposedtangentially to said sidewall portion and wherein said means forsupplying said vapor to said vacuum region includes a crankcase vaporinlet opening in a portion of said chamber which is disposed radiallyinwardly of said curvilinear sidewall portion.

5. A crankcase ventilator system for an internal combustion engine,comprising, in combination, an enclosed vacuum chamber having an atleast partly curvilinear sidewall portion and two end wall portions,combustion gas inlet means for directing combustion gases into saidchamber and along said sidewall portion substantially tangentiallythereof, crankcase vapor inlet means disposed in one of said end wallportions of said enclosed vacuum chamber and spaced radially inwardlyfrom said curvilinear wall portion, gas-vapor outlet means in saidenclosed vacuum chamber disposed substantially tangentially to anotherportion of said curvilinear sidewall portion for directing combustiongases and crankcase vapors outwardly from said enclosed vacuum chamber,means for connection to a portion of the crankcase of an internalcombustion engine to afford communication with the interior of saidcrankcase, crankcase vapor conduit means connecting said crankcase vaporinlet means to said means for connection to said crankcase, combustiongas conduit meansfor connecting a source of combustion gases to saidcombustion gas inlet means, and gas-vapor conduit means extending fromsaid gas-vapor outlet means, said gas-vapor conduit means having an endportion adapted to be disposed in the intake airstream of an internalcombustion engine, whereby combustion gases flowing from the exhaustsystem of an engine into said chamber and along said curvilinear wallportion thereof create a partial vacuum in said vacuum chamber, to drawcrankcase vapors through said crankcase vapor conduit means from saidmeans for connection to said crankcase and entrain said vapors in saidgas flowing through said gas-vapor outlet means so that the resultinggas-vapor mixture may be directed into the intake airstream of anintemalcombustion engine. a

6. A crankcase ventilator system as defined in claim 5 in which saidgas-vapor outlet means and said combustion gas inlet means have anincluded angle of about therebetween.

7. A crankcase ventilator system as defined in claim 5 in which saidgas-vapor conduit means is of larger cross-sectional area than saidcombustion gas inlet means.

8. A crankcase ventilator system as defined in claim 5 in which said atleast partly curvilinear sidewall portion is in the form of an arc of acircle.

9. A crankcase ventilator system as defined in claim 5 in which saidcrankcase vapor inlet means includes a tube disposed in the center ofsaid one of said end wall portions of said chamber, and in which saidtube has a cross-sectional area approximately equal to the crosssectional area of said combustion gas inlet means.

10. A method of recirculating crankcase vapors into the intake airstreamof an internal combustion engine, said method comprising imparting acurvilinear flow pattern to a stream of combustion gases from theexhaust system of said engine to create a vacuum in a region adjacentthe region of curvilinear flow by reason of the centrifugal forcecreated thereby, directing vapors into the vacuum region thus createdfor entrainment into said stream of combustion gases'to form a gas-vaporstream, and directing said gas-vapor stream thus formed into the intakeairstream of said engine.

